Rethinking the Asphalt Roof

Camden architect John Morris on why he no longer specifies a ubiquitous building product

Architect John Morris works out of a renovated 19th-century woolen barn, once part of the Knox Woolen Mill on the tumbling Megunticook River in Camden. It’s a handsome building, with clapboards painted a warm, rosy brown and a dentil molding trim. The roof has been recently re-covered in black standing-seam metal panels, which is to say Morris practices what he preaches: his firm no longer uses asphalt roof shingles for the homes it designs, instead steering clients to metal or cedar-shingle roofs. We spoke with Morris about why he’s turned away from a roofing material whose modest upfront cost has made it a top choice for homeowners.

Q: So, what’s the problem with asphalt-shingle roofs?

A: The issue is really simple: it has to do with the sun and the ozone layer. As we all know, the ozone layer has been depleted, and evidence of the problem has been showing up in the degradation of asphalt-shingle roofs that aren’t very old. We recently had to replace a roof on a project that we did in Rockland about 20 years ago. We were getting leaks in the valleys of the buildings, and it was clearly unusual given the age of the shingles. We found that the manufacturer is willing to stand by its 25-year warranty and will give you however many bundles of shingles you need to re-roof, but that’s little comfort because that’s the easy part of the job. The rough part is the labor involved in ripping off and disposing of all the old shingles — it can be very expensive for the building owner.

Q: Is disposal a problem? I’ve read that asphalt shingles can’t be composted or incinerated because they’re a petroleum product, and it can take more than a hundred years for them to break down in a landfill.

A: Yes, that’s a concern, although there’s no state prohibition on asphalt shingles being taken to the town dump. Some municipal recycling centers accept asphalt shingles and Horch Roofing in Warren recycles all of its re-roofing waste — the asphalt products are used to make paving materials for roads.

Q: As for alternatives, let’s start with metal, since that’s what you chose for your own building. What can you tell us about these roofs?

A: A metal roof is formed in strips that run from the ridge of the roof down to the eaves. You can see the seams standing up between the panels — that’s where the two sheets meet, and it makes for a weatherproof joint. Unless it’s copper, the metal usually has a baked-on finish like Kynar [a factory-applied, resin-based architectural coating] or other paint-like product that protects the metal against weathering, aging, and pollution and gives the roof its color. We typically spec aluminum roofs, which last up to 30 years or more, but the finish degrades over time. It’ll get a powdery look and it won’t retain its crisp color. Copper will last 40 years-plus, but it’s probably twice the cost per square foot of an aluminum roof. When a metal roof eventually corrodes, it can be recycled.

Q: How about maintenance?

A: If you want to spruce up a metal roof because the color has faded, you can spray-paint it [ask your paint dealer or contractor about the best product for your job]. Many colors will age very gracefully, and you’ll never really notice it. Gray, for example, just becomes a slightly lighter gray. Green fades a little bit, but it’s not going to bother most people. The darker colors are not going to retain their pigments as well, but we’re talking decades down the line — 15–20 years before you’re going to have a problem with them. Red fades the fastest because of the pigments used.

About the only problem with metal roofs is when the snow and ice slides off them — it comes off in one big sheet, which can be dangerous. A snow guard, which is a rod mounted about a foot off the bottom of the roof, will keep the snow from coming off all at the same time. The snow will stay there and melt or come off in small amounts.

Q: How do wood shingles compare with asphalt and metal?

A: We don’t have any concerns about cedar roofs deteriorating more rapidly than they used to — I say that as the owner of one on my house and from what we’ve seen on projects we’ve done. Whether Alaskan white or Western red, cedar roofs tend to hold up well — they’re certainly good for 30 years or more.

Q. Do you have to treat the wood?

A. Generally speaking, they’re not treated. Typically, after 15–20 years, they start growing moss and lichens. A case can be made that that’ll rot the wood over time, but both are easily removed by pressure washing with water.

Q: What’s the cost difference between these alternatives and an asphalt roof (typically priced at $4–$7 per square foot)?

A: They are two to three times more expensive, as a rule of thumb. Cedar shingles are going to be more expensive than most metals because of the manual labor involved in installing them.

Q: Can you use metal or cedar on just about any building that currently has asphalt?

A: You can put metal on anything — even a flat roof. We recommend a minimum pitch of 5/12 for a cedar roof, with ventilation under the roof sheathing. A lower pitch will drain more slowly and that can create a more comfortable environment for moss and lichen.

Q: What about architectural style? Metal roofs look great on farmhouses, for example, but are there some buildings where you shouldn’t consider one?

A: There are fewer and fewer such places because metal roofs are becoming ubiquitous! Metal can make buildings with really slowly pitched roofs — say, a 3/12 or a 2/12 — look like warehouses, but those are individual aesthetic judgments.

Cover Image: A cottage designed by John Morris on Megunticook Lake in Camden; photo by Virginia M. Wright